Electrical power generation units, for example renewable energy systems such as solar or wind energy systems, may be connected to an electrical utility grid, and may provide power to the utility grid. It is common for utility companies which own or operate the utility grid to purchase power from the power generation units up to a prescribed power limit, for example 40 kilowatts. The power generation units, especially solar or wind energy systems, may exhibit large variations in power output with respect to the prescribed power limit, so that power output excursions above the prescribed limit are unprofitable.